An electric drive vehicle comprises an engine as a power source, a generator adapted to be driven by the engine, and a traveling motor adapted to be driven with electric power generated by the generator. Power of the traveling motor is transmitted to wheels of the vehicle, thereby making the vehicle travel. As a brake system provided in such an electric drive vehicle, there is known a brake system (see, for example, Patent Literature 1) in which a traveling motor is operated as a generator-type retarder (more particularly, the traveling motor is operated as a generator to convert kinetic energy into electrical energy, thereby actuating the brake).
On the other hand, as a brake system for an industrial vehicle, there is known a brake system (see, for example, Patent Literature 2) having a service brake adapted to operate on the basis of operation of a brake pedal, an electromagnetic retarder provided as an auxiliary brake in an engine power transmission system, a detector for detecting the amount of depression of the brake pedal, and a controller which actuates the retarder in accordance with the amount of depression of the brake pedal detected by the detector. According to this conventional technique, when the amount of depression of the brake pedal is smaller than a predetermined amount, only the retarder is operated; when the amount of depression of the brake pedal is larger than the predetermined amount, both of the retarder and service brake are operated to increase the braking force.
Patent Literature 1: JP-A-2006-166684
Patent Literature 2: JP-A-7-228242